Contrary to popular belief, the United States still has enormous oil resources. Right now, more than 135 years after the birth of the U.S. oil industry, the nation has twice as much oil remaining in its reservoirs as it has so far produced. For every barrel of oil produced to date, two barrels have been left behind. The U.S. oil industry has produced almost 160 billion barrels, but some 350 billion barrels remain as the target of improved oil technologies. Most of this remaining oil, however, is hard to produce. Locked in complex geologic structures, bypassed by conventional technologies, or simply beyond the capability of today's recovery processes, this oil remains elusive.
There are a number of enhanced oil recovery systems available for increasing production from oil and gas reservoirs. These include steam injection, carbon dioxide and/or nitrogen gas flooding, waterflooding with chemicals such as polymers, surfactants, and alkalines, and the use of microbes to produce gases or chemicals underground that increase the mobility of remaining oil.
One of the more popular enhanced recovery systems in the greater Permian Basin area of West Texas and Southeast New Mexico is carbon dioxide ("CO2") flooding. Carbon dioxide flooding has proven to be among the most promising enhanced oil recovery methods for the United States because it takes advantage of plentiful, naturally-occurring carbon dioxide. When CO2 is injected into a reservoir above its minimum miscibility pressure (a miscible flood), the gas acts as a solvent. The CO2 picks up lighter hydrocarbon components, swelling the total volume of oil and reducing the oil's viscosity so that it flows more easily. When a field has already been waterflooded, a tertiary CO2 flood will normally provide incremental recovery of about 8% to about 16% of the original oil in place. When CO2 is used instead of waterflood for secondary recovery, the field can produce up to about 40% of the original oil in place.
Usually, CO2 flooding involves the use of CO2 at existing pipeline pressures, and then injecting the CO2 into the field. When existing pipeline pressures are not high enough to inject the CO2 into the reservoir, the CO2 pressure is boosted with a CO2 pump. Existing dense phase CO2 booster pumping technology uses multistage centrifugal or reciprocating pumps with expensive, double mechanical seals in conjunction with high pressure seal oil systems and seal oil cooling systems. This type of prior art pumping system is typically custom built and housed within large support buildings. Consequently, this type of pumping system is costly, uses large amounts of space, is overly complicated, requires considerable maintenance, and is very time consuming to repair or replace. For the foregoing reasons, there is a need for an improved CO2 pump and pumping system.